From EurekAlert!
Public Release: 14-Jan-2019
Antarctic ice sheet could suffer a one-two climate punch
University of Wisconsin-Madison
MADISON, Wis. — Scientists have long speculated that our planet’s climate system is intimately linked to the Earth’s celestial motions.
The pacing of the most recent ice ages, for example, is attributable to changes in the shape of our planet’s orbit around the sun as well as to cyclic changes in the tilt of the Earth on its axis and its “top-like” wobble on that axis, all of which combine to influence the distribution and intensity of solar radiation.
Now, it turns out that variations in the axial tilt — what scientists call “obliquity” — of the planet have significant implications for the rise and fall of the Antarctic Ice Sheet, the miles-deep blanket of ice that locks up huge volumes of water that, if melted, would dramatically elevate sea level and alter the world’s coastlines.
Writing this week (Jan. 14, 2019) in the journal Nature Geoscience, a team led by Richard Levy of New Zealand’s GNS Science and Victoria University of Wellington, and Stephen Meyers of the University of Wisconsin-Madison describes research that matches the geologic record of Antarctica’s ice with the periodic astronomical motions of the Earth. Comparing the two records, the New Zealand and Wisconsin researchers recapitulate the history of the Antarctic Ice Sheet throughout most of the past 34 million years, starting when the ice sheet first formed.
Underpinning the new perspective of the Antarctic Ice Sheet is a refined assessment of the sensitivity of the Earth’s climate system to changes in obliquity, a powerful tool for probing the icy history of Antarctica.
The research is important because it teases out the pattern of growth and decay of the ice sheet over geologic time, including the presence of sea ice, a thin and fragile layer of frozen ocean surrounding Antarctica. A critical finding suggests that in a world warmed by a growing amount of atmospheric carbon dioxide, a loss of sea ice would likely amplify the cyclic effects of the Earth’s obliquity on the ice sheet as ocean waters warm. A loss of sea ice due to warming climate could trigger instability of the Antarctic Ice Sheet with dire implications for global sea levels.
“What this study does is characterize the growth and decay of the Antarctic Ice Sheet and sheds light on what is forcing it to change,” explains Meyers, a UW-Madison professor of geoscience and an expert on how climate responds to changes in solar radiation from Earth’s astronomical motions. “What has become apparent through this work and other studies is that the Antarctic Ice Sheet isn’t just sitting there. It is vulnerable to decay.”
First measured in the late 1950s by UW-Madison glaciologist Charles Bentley, the West Antarctic Ice Sheet alone contains enough ice to raise sea level by roughly 5 meters. The continental ice sheet is, by far, the largest single mass of ice on Earth. Miles deep in places and containing more than 26 million cubic kilometers of ice. The ice sheet is so heavy, Bentley and his colleagues discovered, that much of the West Antarctic ice sheet sits on land thousands of meters below sea level, making it a marine ice sheet in places.
Marine ice sheets, note Levy and Meyers, are especially sensitive to heat delivered by ocean currents. Fast flowing inland ice streams of the West Antarctic are buttressed by floating ice shelves, which — if diminished or lost — raise the possibility of a runaway flow of West Antarctica’s marine ice.
The new research suggests that a reduction in sea ice due to climate change would erode the barrier keeping the ice sheet — including the parts of it below sea level — in place.
“Sea ice creates a barrier between the ocean and the ice. If we fail to achieve carbon dioxide emissions targets and Earth’s average temperature warms more than 2 degrees Celsius, sea ice will diminish and we jump into a world that is more similar to that last experienced during the early to mid-Miocene,” says Levy, referencing a geological epoch that ended about 14 million years ago when the Earth and its polar regions were much more temperate, with an atmosphere supercharged with carbon dioxide and global temperatures, on average, warmer by 3 to 4 degrees Celsius (7 to 9 degrees Fahrenheit).
To recreate the history of the ice sheet, Meyers and Levy turned to the geologic records surrounding Antarctica and linked them to more distant deep-sea marine sediment cores containing the fossil shells of ocean dwelling microscopic organisms known as foraminifera, or forams. The chemistry of foram shells, oxygen isotopes in particular, contains a signature that documents the ebb and flow of Antarctic ice, Meyers explains. Forams living in the deep ocean accumulate isotopes in their shells, and different isotopes of oxygen can yield a detailed chemical record of the changing volumes of the Antarctic Ice Sheet.
These geological records, say Levy and Meyers, suggest significant variability in the size of the Antarctic Ice Sheet driven by the predictable changes in Earth’s astronomical parameters and threshold changes in atmospheric carbon dioxide levels. Prior to this new research, why the ice sheet responded differently to the same astronomical cycles at different times was a puzzle. Linking those cycles to a detailed chemical record suggests that elevated carbon dioxide in the atmosphere and the resulting loss of sea ice around the Antarctic played a big role in amplifying the effects of changes in the Earth’s astronomical motions on the durability and stability of the Antarctic Ice Sheet.
“All of these data suggest we need to get cracking and reduce our greenhouse gas emissions,” says Levy, noting that 2017 and 2018 saw reduced Antarctic sea ice after several decades of growth. “We don’t want to lose that sea ice.”
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This study was supported by the New Zealand Ministry of Business, Innovation and Employment contract C05X1001 (R.H.L., T.R.N., N.R.G. and R.M.M.) and by National Science Foundation grant EAR-1151438 (S.R.M.).
Same old horseshit.
This article is absurd from so many angles.
Nature Geoscience is a serious journal. It’s not Nature Climate Change.
The paper should be taken seriously.
Not serious enough for proofreading though, since nobody seems to have noticed that “10^5 kyr” means 100,000,000 years, not 100,000.
Obliquity is decreasing and will continue to do so for the next 10K yrs. Climate will become colder before it becomes warmer.
“The pacing of the most recent ice ages, for example, is attributable to changes in the shape of our planet’s orbit around the sun as well as to cyclic changes in the tilt of the Earth on its axis and its “top-like” wobble on that axis, all of which combine to influence the distribution and intensity of solar radiation. Now, it turns out that variations in the axial tilt — what scientists call “obliquity” — of the planet have significant implications for the rise and fall of the Antarctic Ice Sheet”
Maybe I missed it, but where did they explain the mechinism how obliquity is able to affect the AIS? Or did they just discover Milankovitch Cycles? If so, why did they mention CO2 having anything to do with the immeadicy of curtailing our meagre present CO2 emmisions? What is it…CO2 causing ice ages and melting, or long term results of Obliquity within the Milankovitch Cycles? My bet is on obliquity having first order magnitude effect in driving the remaining cycles for amplification and timing for second order affect.
What they try to imply is that if it gets just a leetle warmer then the Milankovich variation will melt the Antarctic Ice Sheet in short order.
From the abstract:
https://www.nature.com/articles/s41561-018-0284-4
Right there the two things I have always insisted are the most important for climate: Obliquity and the temperature gradient between the Equator and Poles. It appears some scientists are starting to realize.
where does he get “supercharged”??
Anal cavity storage.
Now, it turns out that variations in the axial tilt — what scientists call “obliquity” — of the planet have significant implications for the rise and fall of the Antarctic Ice Sheet
Yes indeed, the obliquity is diminishing, meaning less light at the poles, but they would never mention that.
Well, now I have actually read the paper. And what does it amount to? They have made a fairly strong case that the ice volume varies more strongly with the 41 000 year obliquity cycle when the ice volume is smaller, like during the Miocene Climatic Optimum, which seems reasonable. And that is about all.
The connection to, and data on, sea-ice is weak, to put it mildly, and their correlation of cores that consist mostly of hiatuses “at 10^5 kyr resolution” is laughable. By the way, the peer review must have been even sloppier than usual for Nature not to notice that “10^5 kyr” means 100,000,000, not 100,000 years.
Incidentally the decrease in glaciation during the MCO was probably due to partial tectonic blockage of the Drake Passage which increased heat flow to Antarctica.
And of course there is the usual number of idiotic errors in the press release.
“The ice sheet is so heavy, Bentley and his colleagues discovered, that much of the West Antarctic ice sheet sits on land thousands of meters below sea level”
Hardly a new discovery and also wrong. The West Antarctic Ice Sheet is sitting on top of a deep Rift Valley, that’s why. Elementary arithmetics would have shown them that the ice-sheet isn’t nearly heavy enough.
“the West Antarctic Ice Sheet alone contains enough ice to raise sea level by roughly 5 meters.”
However it wouldn’t, exactly because it is situated on top of that deep Rift Valley. Most of the water would be needed to fill out the hole left by the melted ice. Even a total collapse of the WAIS would only raise the sea level about 3 meters.
“Earth and its polar regions were much more temperate, with an atmosphere supercharged with carbon dioxide and global temperatures, on average, warmer by 3 to 4 degrees Celsius”
Seems rather on the low side considering that temperatures in the Antarctic was at least 17 degrees warmer at the time:
https://www.pnas.org/content/105/31/10676
However, since the press-release is intended for journalists they know they can get away with just about anything.
A very good and readable account of the feud between “stabilists” (mostly geologists) and “dynamicists” (mostly climate modellers and paleontologists) about the history of the Antartic Ice Sheet since the Miocene:
https://www.researchgate.net/publication/259437787_Resolving_views_on_Antarctic_Neogene_glacial_history_-_The_Sirius_debate
More researchers ignore that the Holocene was much warmer thousands of years ago.
They have finally admitted that they are climastrologists.
Antarctica is a favourite playground for Warmista Alarms, as it is very remote, very inhospitable and few people go there to make measurements or study volcanoes there that could contradict their alarms.
And unless you have actually been there it is difficult to comprehend just how cold, desolate and glaciated it really is. I know I was surprised even though I had a fair amount of experience from the Arctic. I had visualised something rather like e. g. Nordaustlandet but a bit more so, but reality was very different. The Arctic is a Garden of Eden compared to Antarctica.
Well, now I have read the paper. And what does it amount to? They have made a fairly strong case that the ice volume varies more strongly with the 41 000 year obliquity cycle when the ice volume is smaller, like during the Miocene Climatic Optimum, which seems reasonable. And that is about all.
The connection to, and data on, sea-ice is weak, to put it mildly, and their correlation of cores that consist mostly of hiatuses “at 10^5 kyr resolution” is laughable. By the way, the peer review must have been even sloppier than usual for Nature not to notice that “10^5 kyr” means 100,000,000, not 100,000 years.
Incidentally the decrease in glaciation during the MCO was probably due to partial tectonic blockage of the Drake Passage which increased heat flow to Antarctica.
And of course there is the usual number of idiotic errors in the press release.
“The ice sheet is so heavy, Bentley and his colleagues discovered, that much of the West Antarctic ice sheet sits on land thousands of meters below sea level”
Hardly a new discovery and also wrong. The West Antarctic Ice Sheet is sitting on top of a deep Rift Valley, that’s why. Elementary arithmetics would have shown them that the ice-sheet isn’t nearly heavy enough.
“the West Antarctic Ice Sheet alone contains enough ice to raise sea level by roughly 5 meters.”
However it wouldn’t, exactly because it is situated on top of that deep Rift Valley. Most of the water would be needed to fill out the hole left by the melted ice. Even a total collapse of the WAIS would only raise the sea level about 3 meters.
“Earth and its polar regions were much more temperate, with an atmosphere supercharged with carbon dioxide and global temperatures, on average, warmer by 3 to 4 degrees Celsius”
Seems rather on the low side considering that temperatures in the Antarctic was at least 17 degrees warmer at the time: https://www.pnas.org/content/105/31/10676
However, since the press-release is intended for journalists they know they can get away with just about anything.
Interesting that the figure of 34 million years is included in the fairy tale. I believe this is when Drake’s Passage formed, enabling the Southern Ocean circulation and connection between the Pacific and Atlantic oceans. The hot Pacific waters flooded into the Atlantic resulting in Atlantic warming and Antarctica eventually freezing.
In the northern hemisphere, it is interesting that there is a net transport of heat and water from the Pacific to the Atlantic via the Bering Strait. I wonder how it gets back from Atlantic to Pacific? The Strait is only 50m deep so does not need unrealistic increase in land ice to lose that important inter ocean connection.
The Pacific is Earth’s BIGGEST solar panel:
https://1drv.ms/u/s!Aq1iAj8Yo7jNgxuJI0wR9QXdgceI
Climate on Earth is highly dependent on how the heat collected in the tropical Pacific is transported around the globe. Plate tectonics has been a significant driver of Earth’s climate.
I’m afraid arch-cretin Macron the vaginal monologue was at it for hours this evening in Normandie.
One of his big sales pitches egged on by the sheep, and herded away from the wolves by the CRS and gendarmerie, was to claim you had to buy a NEW diesel car, because old ones should be sold to Africa, because they pollute too much in France.
The twaddle he talked endlessly in technocratic jargon was interspaced with references to the deadly poison gas CO2, and how France had to make an energy transition from (reliable) nuclear power to putting up stacks more intermittent powering wind farms some of them floating, then claiming the new European grid was so wonderful from Germany to France it solved everything, and very soon there would be giant batteries everywhere to make it work happily ever after…
Simply delusional, master propagandist or dangerous lunatic?
This made me so nauseous after watching the train wreck in London, I just had to switch him off.
then I read this crap:-
“https://www.liberation.fr/planete/2019/01/15/la-grande-fonte-de-l-antarctique_1703070”
au secours!
I’ll worry about sea levels when I see panicked UN staff moving their stuff out of their headquarters in Manhattan heading for higher ground. Until then, it’s just noise…..propaganda, really.
True the movement of the Solar system through the universe as the Milky Way galaxy moves, must have some effect, but by far Plate Tectonics must have a far gr eater effect. It is sad that the land mass where todays South Pole now sits, was once the home of Dinosours.
The World e has seen major changes in both movement of the land masses, plus high and low CO2, plus heating and cooling. Yet todays fortune tellers can tell us with accuracy what is going to happen in the future.
Why do our Politicians even listen to such idiots ? Unless of course they want to keep us f frightened.
MJE
“Why do our Politicians even listen to such idiots ?:”
Simple answer, because politicians like Macron, Trudeau etc ARE the idiots.
(with a hidden agenda you can’t know, but can only guess at.
They also claim a state monopoly in violence to protect it).
Am I alone in thinking the Carbon Dioxide reference was stuck in there to get funding, and had little or nothing to do with actual study or its findings?
“Antarctic played a big role in amplifying the effects of changes in the Earth’s astronomical motions on the durability and stability of the Antarctic Ice Sheet.”
___________________________________________________
how shall “Antarctic play [] be a big role in amplifying the effects of changes in the Earth’s astronomical motions”.
Our globe / the shapeless potato / must always be balanced otherwise we would not have a warming problem but would have long since flown out of orbit.
There are 3 Milankovitch cycles, each with their own periodicity. Orbital eccentricity is roughly 100,000 years (combination of a 413,000 year, 95,000 year and 125,000 year cycles), axial tilt is 41,000 years and axial precession of 25,772 years.
The article stated that the cyclic danger was the combination of the axial tilt and orbital eccentricity. But then they completely skip over where we are in those cycles, and their length. Our axial tilt is decreasing and will reach the minimum in about 9,700 years. Our orbit is becoming more circular, thus making the seasons more even. So, as is typical, they state a true fact, i.e. the right combination of axial tilt and orbit eccentricity will maximize warming at the south pole. But they leave out the part on when that is projected to occur.
The comparison of the Mid Miocene Warming event with AGW as a CO2 greenhouse effect thing is not as easy as implied by these authors. There are serious anomalies and paradoxes. Although I have to agree that if you are determined and you try hard enough you can still do it. Pls see
https://tambonthongchai.com/2019/01/17/miocene/